Endocrine

Lipid soluble hormones (steroid,thyroid hormones) Water soluble (peptide,proteins) ReceptorsInside the cell Usually in nucleus Outer surface of cell membrane StorageSynthesis as needed Exception :thyroid hormone Stored in vesicle Plasma transportAttached to proteins that serve as carriers Dissolve in the plasma Half lifeLongShort

Pituitary gland Pituitary Anterior pituitary posterior pituitory

Anterior pituitary: secretes FSH,LH,ACTH,TSH,Prolactin,GH,melanotropin(MSHJ) Derived from oral ectoderm (Rathke’s pouch) Cells in ant pituitary :Acidophilic ---GH and prolactin. Basophilic ---FSH,LH,ACTH,TSH

Posterior pituitary :secretes vasopressin (ADH) And oxytocin,made in hypothalamus and shipped to posterior pituitary via neurophysin Derived from neuroecteoderm.

Thyroid hormone :Iodine containing hormones that control the body’s metabolic rate. Source :Follicles of thyroid.Most T3 formed in target tissues. T3 function ----Brain maturation Bone growth Beta-adrenergic effects Basal metabolic rate

The organization of the thyroid and the distribution of body iodine The functional unit is follicle. The lumen is filled with thyroglobulin to which covalent bound large numbers of thyroid hormone molecules Surrounds the lumen are follicles cells,which function to both synthesize and release thyroid hormones. These relationships are schematically

Oxidation, iodination and coupling :All three process catalyzed by peroxidase. Secretion of thyroid hormone Endocytosis:Piece of follicular colloid taken back into the follicle by endocytosis.

Transport of thyroid hormone T4 has higher affinity for binding proteins. Half –life of T4 is greater than that of T3. T4 half-life=6days T3 half-life =1day Most of the peripheral activity results from the conversion of T4 to T3.